This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 9802751-9 filed in Sweden on Aug. 18, 1998; the entire content of which is hereby incorporated by reference.
The present invention relates to a method of patterning metallic building elements and to a patterned metallic building element, said building element being produced in accordance with the method of patterning metallic building elements, wherein the measurement accuracy obtained can lie in the sub-micrometer range. The building elements produced in accordance with the method may be used, among other things, as carriers for optoelectrical and electrical god components, and fibers and waveguides. The metallic building elements may also be used as micromechanical building blocks or as parts of a mould cavity for injection moulding or compression moulding purposes.
The technique at present used for mounting optoelectric laser chips in low-cost applications most often includes soldering of a chip to a ceramic or silicon carrier. Alignment between the optical active part of a laser and the core of fiber can be achieved by virtue of the possibilities of etching silicon with great precision and the use of a technique in which the laser is firmly soldered and aligned with the aid of the surface tension forces present in a solder melt. Some sort of gluing technique is normally used, for instance, to fasten pin diodes to a carrier. Optical mirrors produced by etching in silicon and metallizing the surface are often used to reflect light from a fiber to a pin diode.
When an optoelectric laser chip is to be mounted on a ceramic carrier or a silicon carrier, there often arises the problem of dissipating heat generating in the chip. Varying chip temperature can, in operation, influence the transmitted wavelength. An excessively high operating temperature can also shorten the useful life of the chip. Furthermore, ceramic and silicon carriers often demand a high price, due to the relatively complicated manufacturing processes involved.
The technique described in accordance with the invention enables the cost-effective production of building elements that can be used either free-standing or as a substantial, pattern-creating part in a mould cavity intended for injection moulding or compression moulding purposes. The technique can be used to create metallic carriers that have low thermal resistance and good electrical conductivity, with the intention of preventing damage to electrical and optoelectrical chips, such as lasers, due to high or varying temperatures.
With a starting point from a silicon original or master, which can be etched to sub-micrometer precision and then plated with a metal, such as nickel, on the silicon surface, it is possible to produce a nickel shim with a precision and a surface fineness that will still lie in the sub-micrometer range. If necessary, the rear side of the shim can then be made flat prior to separating silicon from nickel. Subsequent to removing the silicon master, a photo-sensitive material, in liquid form or in film-form, can be used to create cavities that reach down to the nickel shim. These cavities can then be metallized, to form three-dimensional building elements of high precision.
These metal precision elements can then be used, for instance, for effectively conducting away heat from lasers or other heat-generating chips. The precision, surface fineness and measurement accuracy that can be achieved with the method also enable optoelectrical, components, such as, e.g., lasers with optical single-mode fibers and sharp optical mirrors to be aligned. The method also provides building elements that can conduct electric current, which enables three-dimensional electric conductors and electrodes to be produced to a specified thickness. The template or form produced in accordance with the aforedescribed method can also be used repeatedly in plating cycles, therewith contributing to low-cost production of the plated building elements.
The invention will now be described in more detail with reference to a preferred embodiment thereof and also with reference to the accompanying drawings.